Last year, when Clark finished a close second in the annual Memorial Day track race driving a Lotus powered by a highly-tuned 4.2-litre push-rod Ford V8 engine, it looked as though the days of the Conventional Indianapolis “roadster” with front-mounted 4-cylinder Offenhauser engine were numbered. Clark had been so close to winning with the near-stock power unit, that news of a new pure-racing four-overhead-camshaft Ford V8 engine for this year seemed to make victory a foregone conclusion. The only opposition to this theory was the fact that many American racing car builders were taking delivery of this new racing engine from Detroit and they were looking into this question of rear-engined racing cars. Mickey Thompson had already done a lot of work with a fair measure of success on rear-engined cars, but he was still comparatively new to Indianapolis. However, the Californian designer A. J. Watson was at work on a rear-engined project, and his conventional “roadster” cars had won at Indianapolis for more years than most people can remember. In addition to this activity those who still favoured the front-engine car with the known 500-Mile qualities of the Meyer-Drake built Offenhauser engine were making big efforts to reduce the weight of their cars, which would not only give improved high-speed acceleration out of the turns, but would give tyres and fuel consumption an easier time. Although it seemed that Lotus and Ford must win the race this year there was a tendency to forget that the Americans had been working for a whole year on this project alone, whereas Lotus and Ford were fitting it into a vast annual racing programme.
The practice and qualifying sessions sorted out the 33 starters and amongst these were thirteen rear-engined cars, seven with Ford V8 engines and six with Offenhauser engines, among the latter being Brabham with his own car. There were two front-engined Novi V8 cars and the 4-w-d Ferguson-Novi V8, while the rest of the runners were conventional Indianapolis “roadsters” with front-mounted Offenhauser engines. It was significant that the three cars on the front row were all powered by Ford V8 four-camshaft engines, Clark with the latest Lotus 34, Marshmann with one of last year’s Lotus 29 cars, and Ward with an A. J. Watson-built rear-engined car with Ford V8 power unit. Clark had made fastest qualifying speed with 158.828 m.p.h. average for the regulation four flying laps, his fastest single lap being 159.337 m.p.h. This had been done using alcohol fuel, whereas in the race itself he was running on straight petrol, as were most of the Ford engines, except that of Rodger Ward. Chief opposition to the “new” brigade was clearly to come from Parnelli Jones and A. J. Foyt with front-engined Offenhauser-powered Watson-built cats, and they were both in the second row alongside Gurney. Another unusual variation in the line-up was that the Lotus cars of Clark and Gurney were running on Dunlop tyres, against the more usual Firestone equipment used by everyone else.
The race started in fine style, with Clark in the lead and setting a record-breaking pace, but then tragedy intervened, for as the second lap was being completed Dave McDonald in one of the Thompson rear-engined cars spun and hit the retaining wall. He was in the middle of the tightly packed field and seven cars became involved in a multiple crash. It was so bad that the race had to be stopped, and in the crash Eddy Sachs was killed and McDonald received injuries from which he later died. It was one and three-quarter hours later that the race was restarted, the remaining runners lining up nose-to-tail in the order that they had been on the second lap, with Jim Clark heading the line. Another rolling-start was given and the race got away at record lap speeds. For a time Lotus-Ford cars filled the first three places, in the order Clark, Marshmann, Gurney; then Marshmann led and at to laps the average speed was a fantastic 154.917 m.p.h. However, it was not a Lotus day, for Gurney had to make a pit-stop for attention to the fuel-system, then Marshmann went out with a serious oil leak, and finally Clark subsided onto the grass on the infield when his left rear suspension collapsed. This left the Offenhauser-engined cars of Jones and Foyt firmly in the lead, followed by Ward in the rear-engined Watson-Ford, Hansgen in a rear-engined Offenhauser car and Ruby in another “roadster.” Jones was put out of the race when his car caught fire just as he was leaving the pits after a refuelling step, and from that moment on A. J. Foyt in his last-year’s front-engined Offenhauser-powered car was unchallenged. The Lotus challenge had died after 40 of the 200 laps, and though Gurney continued for some time he was eventually withdrawn when it was found that the tyres were overheating and bits were coming off the treads. Foyt drove a very regular race, winning at record speed, and Ward chased him all the way but was nearly a lap behind at the finish, and was the only Ford-powered car to finish, the remaining runners all having Offenhauser engines, with the exception of a lone Novi V8. The 4-w-d Ferguson-Novi, driven by Unser, was eliminated in the multiple crash, as were two of the Ford V8-engined cars, those of Sachs and McDonald.
The winner made two refuelling stops, running on alcohol fuel, and did not change his Firestone tyres, so the race proved a victory for the conventional over the radically different, but the battle for Indianapolis honours between the “old” and the “new” will undoubtedly continue for another year.